Effects of freeze-thaw damage on the bond behavior of concrete and enhancing measures

Abstract

This paper presents a comprehensive study to investigate the effects of freeze-thaw damage coupling with sustained loading on the bond behavior of various concrete, through a series tests of loading, freeze-thaw cycles and bond-slip. The results indicate that the freeze-thaw damage leads to the decrease in the bond behavior of concrete. The effects of sustained loading on the bond behavior of ordinary concrete is not obvious when the imposed freeze-thaw damage is slight. Whereas, the bond behavior considerably decreases when the concrete suffered a serious freeze-thaw damage combined with the sustained loading; such as, the bond behavior with the sustained loading of 30%ft and 50%ft decrease by 22.8% and 48.5% compared with that without loading, after 50 freeze-thaw cycles. Attributing to the superior freeze-thaw resistance of air-entrained concrete, the decrease in the bond behavior of air-entrained concrete is not obvious, under the environment of freeze-thaw cycles coupling with sustained loading. Although the ultimate bonding stress of SHCC repairing concrete presents a small decrease compared with that of ordinary concrete, the peak slip significantly increases after the same freeze-thaw cycles, and the pull out failure happened in SHCC repairing concrete, rather than the splitting failure. Furthermore, increasing stirrup reinforcement ratios can well restrain the cracks development on the bonding interface of SHCC repairing concrete.